Marie Antoinette was Austrian. I think liberals get defensive over nationalities they believe to be inferior, thus need special protections. Hence you can were lederhosen and a bayernhute and it's completely fine.What is the beef? Its a costume. People wear cultural clothes from around the world, occupations and throughout history. Costumes don't have to be scary or fictional. Were shawls and sombreros never worn? They were the fashion of Mexican bands and restaurants for decades.
Seems everyone is "offended" by something some time. When did people get so thin skinned? Lots of people dress and day of the dead in face and dress. Is that offensive as well?
University should not have to apologise.
If they dressed as Marie Antoinette, should the french be objecting? Its a costume.